37,463 research outputs found
Irregular and multi--channel sampling of operators
The classical sampling theorem for bandlimited functions has recently been
generalized to apply to so-called bandlimited operators, that is, to operators
with band-limited Kohn-Nirenberg symbols. Here, we discuss operator sampling
versions of two of the most central extensions to the classical sampling
theorem. In irregular operator sampling, the sampling set is not periodic with
uniform distance. In multi-channel operator sampling, we obtain complete
information on an operator by multiple operator sampling outputs
ASIdE: Using Autocorrelation-Based Size Estimation for Scheduling Bursty Workloads.
Temporal dependence in workloads creates peak congestion that can make service unavailable and reduce system performance. To improve system performability under conditions of temporal dependence, a server should quickly process bursts of requests that may need large service demands. In this paper, we propose and evaluateASIdE, an Autocorrelation-based SIze Estimation, that selectively delays requests which contribute to the workload temporal dependence. ASIdE implicitly approximates the shortest job first (SJF) scheduling policy but without any prior knowledge of job service times. Extensive experiments show that (1) ASIdE achieves good service time estimates from the temporal dependence structure of the workload to implicitly approximate the behavior of SJF; and (2) ASIdE successfully counteracts peak congestion in the workload and improves system performability under a wide variety of settings. Specifically, we show that system capacity under ASIdE is largely increased compared to the first-come first-served (FCFS) scheduling policy and is highly-competitive with SJF. © 2012 IEEE
Resonant conditions for Love wave guiding layer thickness
In this work we report a systematic investigation of polymer overlayer thickness in a Love wave device working at a fundamental frequency of 110MHz and at the 330MHz harmonic. At both frequencies we observe the initial reduction in insertion loss associated with a Love wave device. Significantly, we also observe a series of resonant conditions as the layer thickness is further increased. The separation of these resonances is attributed to an increase in thickness of half of the acoustic wavelength in the polymer
Pulse mode operation of Love wave devices for biosensing applications
In this work we present a novel pulse mode Love wave biosensor that monitors both changes in amplitude and phase. A series of concentrations of 3350 molecular weight poly(ethylene glycol) (PEG) solutions are used as a calibration sequence for the pulse mode system using a network analyzer and high frequency oscilloscope. The operation of the pulse mode system is then compared to the continuous wave network analyzer by showing a sequence of deposition and removal of a model mass layer of palmitoyl-oleoyl-sn-glycerophosphocholine (POPC) vesicles. This experimental apparatus has the potential for making many hundreds of measurements a minute and so allowing the dynamics of fast interactions to be observed
Scalable gate architecture for densely packed semiconductor spin qubits
We demonstrate a 12 quantum dot device fabricated on an undoped Si/SiGe
heterostructure as a proof-of-concept for a scalable, linear gate architecture
for semiconductor quantum dots. The device consists of 9 quantum dots in a
linear array and 3 single quantum dot charge sensors. We show reproducible
single quantum dot charging and orbital energies, with standard deviations less
than 20% relative to the mean across the 9 dot array. The single quantum dot
charge sensors have a charge sensitivity of 8.2 x 10^{-4} e/root(Hz) and allow
the investigation of real-time charge dynamics. As a demonstration of the
versatility of this device, we use single-shot readout to measure a spin
relaxation time T1 = 170 ms at a magnetic field B = 1 T. By reconfiguring the
device, we form two capacitively coupled double quantum dots and extract a
mutual charging energy of 200 microeV, which indicates that 50 GHz two-qubit
gate operation speeds are feasible
Sensitivity of Ru(bpy)_2dppz^(2+) Luminescence to DNA Defects
The luminescent characteristics of Ru(bpy)_2dppz^(2+) (dppz = dipyrido[3,2-a:2′,3′-c]phenazine), a DNA light switch, were investigated in the presence of oligonucleotides containing single base mismatches or an abasic site. In water, the ruthenium luminescence is quenched, but, bound to well matched duplex DNA, the Ru complex luminesces. Here we show that with DNAs containing a defect, rac-, Δ-, and Λ-Ru(bpy)_2dppz^(2+) exhibit significant luminescent enhancements above that with well matched DNA. In the presence of a single base mismatch, large luminescent enhancements are evident for the Δ-Ru isomer; the Λ-isomer shows particularly high luminescence bound to an oligonucleotide containing an abasic site. Similar increases are not evident with two common DNA-binding organic fluorophores, ethidium bromide and TO-PRO-3. Titrations with hairpin oligonucleotides containing a variable mismatch site show correlation between the level of luminescent enhancement and the thermodynamic destabilization associated with the mismatch. This correlation is reminiscent of that found earlier for a bulky rhodium complex that binds mismatched DNA sites through metalloinsertion, where the complex binds the DNA from the minor groove side, ejecting the mismatched bases into the major groove. Differential quenching studies with minor and major groove quenchers and time-resolved emission studies support this metalloinsertion mode for the dppz complex at the defect site. Certainly these data underscore the utility of Ru(bpy)_2dppz^(2+) as a sensitive luminescent reporter of DNA and its defects
Spin Dependence of Interfacial Reflection Phase Shift at Cu/Co Interface
The spin dependent reflection at the interface is the key element to
understand the spin transport. By completely solving the scattering problem
based on first principles method, we obtained the spin resolved reflectivity
spectra. The comparison of our theoretical results with experiment is good in a
large energy scale from Fermi level to energy above vacuum level. It is found
that interfacial distortion is crucial for understanding the spin dependence of
the phase gain at the CuCo interface. Near the Fermi level, image state
plays an important role to the phase accumulation in the copper film.Comment: 6 papges, 3 figures, accepted by Physical Review
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